Glossary of boating terms | Lake

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Lake

A lake (from Latin lacus) is a body of water larger and deeper than a pond. Globally, lakes are greatly outnumbered by ponds: of an estimated 304 million standing water bodies worldwide, 91% are 1 hectare or less in area (see definition of ponds) (Downing et al 2006). Small lakes are also much more numerous than big lakes: in terms of area, one third of the world's standing water is represented by lakes and ponds of 10 hectares or less (Downing et al 2006). However, large lakes contribute disproportionately to the area of standing water with 122 large lakes of 1000 km2 or more representing about 29% of the total global area of standing inland water.

Until recently, there has been considerable uncertainty about defining the difference between lakes and ponds. For example, limnologists have defined lakes as waterbodies which are simply a larger version of a pond, or which have wave action on the shoreline, or where wind induced turbulance plays a major role in mixing the water column. None of these definitions completely excludes ponds and all are difficult to measure. For this reason there has been increasing use made of simple size-based definitions to separate ponds and lakes. In the United Kingdom, for example, the charity Pond Conservation - which works to protect all types of freshwater ecosystem - has defined lakes as waterbodies of 2 hectares or more in area (Willliams et al 2004). Elsewhere, other workers have treated lakes as waterbodies of 5 ha and above, or 8 hectares and above (see defintions of pond). Charles Elton, one of the founders of ecology, regarded lakes as waterbodies of 40 hectares or more, a value somewhat larger than modern studies would suggest appropriate (Elton and Miller 1954).

The vast majority of lakes on Earth are fresh water, and most lie in the Northern Hemisphere at higher latitudes. In ecology the environment of a lake is referred to as lacustrine. Large lakes are occasionally referred to as "inland seas", and small seas are occasionally referred to as lakes. Smaller lakes tend to put the word "lake" after the name, as in Green Lake, while larger lakes often invert the word order, as in Lake Ontario, at least in North America. In some places, the word "lake" does not correctly appear in the name at all (e.g., Windermere in Cumbria).

Over 60% of the world's lakes are in Canada; this is because of the deranged drainage system that dominates the country. The license plate of the Canadian province of Manitoba used to claim "100,000 lakes" as one-upmanship on Minnesota, whose license plates boast of it being the Land of 10,000 Lakes.

Finland is known as The Land of the Thousand Lakes (actually there are 187,888 lakes in Finland, of which 60,000 are large),[1] and the U.S. state of Minnesota is known as The Land of Ten Thousand Lakes.

Only one lake in the English Lake District is actually called a lake; other than Bassenthwaite Lake, the others are all "meres" or "waters". Only six bodies of water in Scotland are known as lakes (the others are lochs): the Lake of Menteith, the Lake of the Hirsel, Pressmennan Lake, Cally Lake near Gatehouse of Fleet, the saltwater Manxman's Lake at Kirkcudbright Bay, and The Lake at Fochabers. Of these only the Lake of Menteith and Cally Lake are natural bodies of fresh water.

Most lakes have a natural outflow in the form of a river or stream, but some do not and lose water solely by evaporation or underground seepage or both. They are termed endorheic lakes (see below).

The term "lake" is also used to describe a feature such as Lake Eyre, which is a dry basin most of the time but may become filled under seasonal conditions of heavy rainfall.

Many lakes are artificial and are constructed for hydro-electric power generation, recreational purposes, industrial use, agricultural use, or domestic water supply.

Evidence of extraterrestrial lakes exists; "definitive evidence of lakes filled with methane" was announced by NASA as returned by the Cassini Probe observing the moon Titan, which orbits the planet Saturn.